You can’t do it.
UDK supports importing LODs from a single FBX using the FBX LOD groups, this is awesome, except that you can only make this in 3dsmax by using the Level of Detail utility. The LOD utility is not scriptable, and is not cool for workflow. It looks like most of the function of LOD sets hinges on the visiblity:LOD_Controller controller so I figured I could just build the LODs on export through script. Some of my favorite mxs reference:
The LOD_Controller controller is not creatable by MAXScript. It can only be created using the Level of Detail utility.
There are no additional properties for LOD_Controller.
It looks to me like the best option to get around the LOD utility would be to edit an ascii FBX post export, and build the FBX lod groups that way.
Has anyone had the need to script the LOD utility? Or otherwise made FBX LOD groups without it?